This invention relates generally to intraluminal catheters, and more particularly to balloon dilatation catheters for performing angioplasty procedures.
In a PTCA procedure a guiding catheter having a preformed distal tip is first percutaneously introduced into the vascular system of a patient. The distal end of the guiding catheter is directed into the ostium or opening of the desired coronary artery and seated within the ostium by twisting or torquing the catheter from its proximal end which extends out of the patient.
A guidewire is advanced proximally through the guidewire lumen of the balloon catheter until only the distal tip of the guidewire extends out of the distal tip of the balloon catheter. The guidewire-balloon catheter assembly is inserted into the proximal end of the guiding catheter and advanced therethrough until the distal tip of the guidewire reaches the seated distal end of the guiding catheter.
The guidewire is then advanced out of the distal end of the guiding catheter and through the coronary artery until the distal tip of the guidewire is in position, typically several centimeters beyond the stenosis, to anchor the guidewire during the angioplasty procedure. Once the guidewire is in position, the balloon catheter is advanced out of the distal end of the guiding catheter over the guidewire until it reaches a desired location within the artery to be dilated, with the working section of the balloon traversing the stenosis to be dilated. Once in place across the stenosis, the balloon is inflated one or more times to compress the atherosclerotic plaque against the inside of the artery wall and to otherwise expand the artery. After inflation the balloon is then deflated so that blood flow is resumed through the now dilated artery and the dilatation catheter assembly and guiding catheter can be removed.
Further details of dilatation catheters, guidewires and devices associated therewith for angioplasty procedures may be found in the U.S. Pat. No. 4,323,071 to Simpson et al.; U.S. Pat. No. 4,439,185 to Lundquist; U.S. Pat. No. 4,468,224 to Enzmann et al.; U.S. Pat. No. 4,516,972 to Samson; U.S. Pat. No. 4,538,622 to Samson et al., U.S. Pat. No. 4,554,929 to Samson et al.; U.S. Pat. No. 4,616,652 to Simpson; U.S. Pat. No. 4,638,805 to Powell; U.S. Pat. No. 4,748,982 to Horzewski et al.; U.S. Pat. No. 4,748,986 to Morrison et al.; U.S. Pat. No. 4,821,722 to Miller et al.; and U.S. Pat. No. 4,898,577 to Badger et al. which are all hereby incorporated in their entirety by reference.
Another type of dilatation catheter is the rapid exchange type dilatation catheter, such as those available from the assignee of the present invention, Advanced Cardiovascular Systems, Inc., under the trademark ACS RX.RTM. Coronary Dilatation Catheter. This catheter is described and claimed in U.S. Pat. No. 5,040,548 (Yock), U.S. Pat. No. 5,061,273 (Yock) and U.S. Pat. No. 4,748,982 (Horzewski et al,) and has a short guidewire receiving sleeve or inner lumen extending through the distal portion of the catheter. The sleeve preferably extends proximally a distance of at least about 10 cm and usually not more than about 50 cm from a first guidewire port in the distal end of the catheter to a second guidewire port in the catheter spaced proximally from the inflatable balloon of the catheter. A slit may be provided in the catheter wall which extends distally from the second guidewire port, preferably to a location proximal to the proximal end of the inflatable balloon to aid in the removal of the catheter from a guidewire. The structure of the catheter allows for the rapid exchange of the catheter without the need for the use of an exchange wire or adding a guidewire extension to the proximal end of the guidewire. The design of this catheter has been widely praised by the medical profession and has met with much commercial success in the market place because of its unique design.
A substantial improvement in the rapid exchange type dilatation catheters, such as described above, has recently been made by McInnes et al. which is described in copending applications Ser. No. 07/476,056, filed Feb. 7, 1990 and Ser. No. 07/541,264 filed Jun. 19, 1990, both entitled READILY EXCHANGEABLE PERFUSION DILATATION CATHETER, which are incorporated herein by reference. In this readily exchangeable dilatation catheter, perfusion ports are provided in the catheter shaft proximal and distal to the balloon which are in fluid communication with the guidewire receiving inner lumen to allow blood to perfuse distal to the catheter when the balloon was inflated.
In an angioplasty procedure with an over-the-wire dilatation catheter as discussed above, the balloon dilatation catheter is guided along the guidewire to the appropriate arterial location. However, if the catheter is too stiff longitudinally, it can fail to track over the guidewire and in some instances can pull the guidewire out of a branch of the artery.
If the catheter has insufficient radial stiffness, kinking can occur when the catheter traverses a turn but a portion of the catheter folds, i.e. kinks, instead of simply curving. Once a kink occurs, it prevents any further pushing force from being applied to the catheter and it can limit the flow of fluid through the catheter which is necessary for inflation of the catheter.
Thus, it is advantageous to have an over-the-wire catheter which has sufficient longitudinal flexibility to negotiate the curves and to track well over a guidewire in the vascular system but which is sufficiently radially rigid to prevent kinking. The catheter of the present invention provides such advantages.